To my knowledge, all colleges/universities are refunding room and board for the times campus is closed. Legally I don't think there's an option.
Online teaching is difficult. It's not a good substitute for all parts of the in-person experience.
Yellow highlighters' coloring is called 'Solvent Green 7' and has a peak at about 494nm.
You can buy filters for lenses that will knock out certain bandwidths of light and keep the rest coming into the camera. These are called notch filters, as they take a notch out of the light.
There just so happens to be a notch filter that should know out the yellow highlighter color. Meaning that the light reflected from a yellow highlighter will not enter into the camera.
https://www.thorlabs.com/thorproduct.cfm?partnumber=NF488-15
They are not cheap though, and as such, I've not tried this at home to see how well it works.
Other solutions may exist at to the ideas that these people may have about how your webcam is working. I'd experiment with other lenses, polarized filters, exposure times, etc.
That said, studying is a lot easier than trying to jerry-rig your webcams.
Alternatively, one could run a VM with the monitoring software, and have a separate window with notes. As long as the mirror is angled so to hide a small portion of the screen that should be good enough.
To build on your physical solution using polarization: that's easier. You can apply a polarized filter to the webcam (you can get one from an old pair of 3d glasses) and then have the notes on a secondary screen that will then look completely dark on webcam. Maybe lay the device on a black background so it's not obvious that there's a "turned off" device and you're done.
This is all a fun thought experiment. I don't have invasive professors, thankfully. They simply made all tests open book and raised the difficulty of the questions accordingly. That being said, I enjoy trying to work arounf hypothetical limitations...
I'm hard-pressed to think of many subjects where an "open book" test isn't a better option, even for in-person classes. If a cheat sheet can help during a test, then it's asking predictable questions and measuring regurgitation.
My wife pointed out language tests to see if students can use the skills on the fly, but I can't think of another good case. This should be a time for schools to find which teachers are just going for easy-to-write instead of useful tests.
The caveat to all of these is that they take more work for teachers, so many prefer not to use them.
1. The "self-taught" style. This one is being done by my linear algebra class: the prof tells us which chapters to read, sends out notes, and some recommended problems. Periodically, he sends out a take-home test; we work it and send him the answers. This style is helped by the fact that our book is short and concise enough to teach but still be readable. No one wants to read if a chapter takes hours. This approach works great for me, but it requires a more self-directed student to function.
2. The "micro-manager" style. This one is being done by my physics class: the prof uses online, checked homework, multiple zoom calls, requires us to record videos of ourselves solving problems in a "tutorial style", gives on-line quizzes, and attempts to give the same tests on-line as were given in-person. This results in horrible, invasive solutions that give a "proctor" remote access to one's computer, require one to use a webcam to be monitored, and require one to show the space around him using a mirror. This style is awful, wastes colossal amounts of time, but is the option on which teachers fall back when they lack confidence in their students to be self-directed.
Most teachers are going for option 2, which is worse than in-person learning. This may sound cynical, but mot of the tools for "active learning" or "on-line engagement" make students' lives harder, waste their time, and offer no benefit beyond an administrator feeling as though he's "done something".
Edit: can any current student tell me if y'all are getting refunded for room and board, at least partially? Y'all paid for something and are being prohibited from using it, so that seems reasonable.