It's not so hard to create a keyboard layout using the Microsoft Keyboard Layout Creator (MSKLC) [0]. I don't know if it can do everything that uncap can, but I'm pretty sure it can do most things, and it doesn't need a separate program to be running, because the keyboard layout is just installed as part of Windows.
A number of my favourite keyboard layouts are at http://keyboards.jargon-file.org/ (notably Pseudo-VT320, which turns AltGr into a Linux-like compose key).
It looks a bit old, but works fine under Windows 8 and 10.
[0] https://msdn.microsoft.com/en-us/globalization/keyboardlayou...
You cannot remap Caps Lock key with Microsoft Keyboard Layout Creator. If it were really that straightforward, then Vim users would not be forced to rely on registry hacks or tools like Uncap or AutoHotKey to map Caps Lock to Escape [0].
If you dislike editing Windows registry like me, you need a separate program to be running.
Project URL: https://github.com/susam/uncap#uncap