Can someone spy on me through my Mac's Camera? Is there any way to know for sure?

Yes, the light would have to be on to let you know it's active.

Unless you download and install a lot of illegal software, the chances anyone else has any control at all of your Mac is pretty much zero.

Are you asking because you received an email saying they have a recording of you doing naughty things, and to pay a BitCoin ransom? If so, it's a scam. Delete and ignore.

The webcam status light would be on when it is recording. That is the reason for the light; that you know when the cam is in use, and someone could be watching.

The webcam can’t be accessed directly remotely. It only happens when there is an application in use that accesses the webcam. Applications need your (one time) permission to access the camera (on recent version macOS). If you are confident about the software on your computer, and if it is running or not, and if you are not Mr Zuckerberg, then you do not have much to worry about.

Keep your software up-to-date, so that you have the latest security patches.

Urquhart1244 wrote: The webcam status light would be on when it is recording. That is the reason for the light; that you know when the cam is in use, and someone could be watching.

Kurt Lang wrote: Yes, the light would have to be on to let you know it's active.

Actually, a few years back there were some serious incidents where computer webcams were commandeered remotely without the LED light being turned on.

Macs were involved in some of these cases. Probably the most serious case, dubbed WebcamGate, involved over 2000 MacBooks given to students by their high school. It resulted in a class-action lawsuit after it was revealed that the school district had taken over 66,000 surreptitious images of students through the webcams, many when the students were in their own homes. In that case the LED light would momentarily flicker but did so quickly that few students noticed it. In other cases, however, the LED light was completely disabled.

The point is, while not a prevalent problem, it can be done. That's why many people, myself included, keep a sticky note over the webcam unless we are actively using the webcam ourselves under our own control. This is also why many webcams now come with a built-in shutter cover that users can close over the camera when not using it.

The main point I was trying to make was that it is technically possible for the webcam to be operational without the LED light being turned on. I cited the case to provide some very real-world proof that it can be done. 🙂

I haven't heard of many cases of it happening through malware, but it's as possible as any other malware that's around. Best to be as careful as we can be.

In the case you mentioned (it occurred in my old school district), there was software installed on the computers by the owners of the computers that did that. I'm not defending what the school district did (it was beyond stupid) but, it wasn't malware that some individual user accidentally installed.