Micro Snitch is an unobtrusive Mac OS X app that monitors and reports any microphone and camera activity to help you figure out if someone’s spying on you.
Any current microphone or camera activity is displayed in the menu bar. The menu also shows a list of connected audio/video devices.
The app is able to identify and provide details both about the device active and the service that is controlling it.
Micro Snitch is now available in English, French, German, Japanese, Portuguese, Spanish and Chinese (both simplified and traditional).
Since Micro Snitch uses very few resources, you can keep it running at all time.