Grab a piece of non-transparent tape, and cover it over your webcam (If you are on a laptop). And if you have an external webcam, always point it towards a wall if you are not using it or unplug it. Hacking webcams is bootcamp exercise for a hacker and not always are these files spotted by antivirus/malware applications.
Remember, they don't always need to film you in particular. If they see an empty living room and know you've left the house they could already have what they want to know. And not every hacker exposes himself by sending fake error messages. If they are after something, they try to stay in the background.
I'm not saying you are hacked, but be aware of it as it is very easy for people to hack those. Keeping the cam covered is always a good practise. Perhaps your webcam is defective, check your model number and see if other people are reporting the same issue with the same model. If no one else reports it, try to remember if you have opened any suspicious emails or downloaded a file from someone whose browsing habits aren't too responsible.