Is it possible to turn on the light that indicates that the camera (on a MacBook) is on without turning on the camera? (Then it could be used as an indicator for something else.)
A couple years ago there was rumours about malware being able to run the camera without having the light on. Both LED and Camera are driven by the Apple SMC (System Management Controller) and are linked together far below OSX user level.
Since then Apple most probably have put extra efforts to avoid usage of one without the other.