Use the built-in camera
If your Mac or display has a built-in iSight, FaceTime, or FaceTime HD camera, you can use it to take pictures or videos using Photo Booth, and to make video calls using FaceTime.
Turn the camera on: A green indicator light beside the camera glows when an app that uses the camera is open.
Turn the camera off: Close the active app window. The green indicator light turns off, showing that the camera is off and video has stopped.