Jesus Christ, guys. Do you use Linux?

Just blacklist the webcam module to preventing it from loading whenever the system boots. Want to use the webcam? Load the module manually.

# modprobe uvcvideo

Want to unload the camera again? Easy.

# modprobe -r uvcvideo

Generally, it's the uvcvideo module, but it might change from system to system.

A malicious code would need root access to your system to load/unload the webcam module. If someone has root access to your computer/to execute code in your computer, you're in MUCH, much deeper shit than if you let someone film you. Seriously. Specially if you use your computer for money transactions or talk about important stuff to people.