It’s called DroidCam, and it really works, Windows and Linux.
Under Linux you’ll need kernel module compilation capability, headers only for source. If you use the Adobe Flash Player for camera, or any other V4L version 1 application, you’ll want to start it like the below for the Pale Moon web browser:
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so palemoon