How do you know if someone has hacked your webcam?

I noticed that the little light beside my webcam was on. I got paranoid and shut my laptop, but when I opened it back up the light was off. It didn't shut down any programs so it wasn't on because of a program that uses a webcam.
Update: So I just found a cyberlink youcam thing on my computer? I don't know much about computers so I'm not sure what this is.
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