After reading about how hackers have taken control of a MacBook's iSight camera to spy on the person sitting in front of it, you might start to get a feeling that someone is watching you. Just because you're paranoid doesn't mean they aren't after you, after all. Making matters worse, hackers have been able to spy on people without triggering the little green light that tells you your iSight camera is active.
You can simply cover your iSight camera with a piece of tape or use an app to disable it, but if you want to continue to use your MacBook's webcam for FaceTime and Skype and the like, then it's annoying to have to remove the piece of sticky tape (and its residue) or reactivate the camera.
Monitor instead of disable
If the hackers make you disable your webcam, then they've already won. A better course of action is to monitor your iSight camera so you know when it's being used. MacOS doesn't let you do this natively, so you'll need to turn to a third-party app: OverSight.
OverSight is a free app that installs quickly and places an icon in your menu bar to let you know it's running. When an app accesses the iSight camera, you'll get a notification like this:
Bonus: OverSight will also tell you when your microphone is being used:
You'll get these notifications whether you are using FaceTime or Skype or a hacker is tunneling into your machine and accessing the camera. Better to have to ignore OverSight's notifications when you are using the iSight camera than not get them when a hacker is using the iSight camera to spy on you, no?