Is it normal to have a fear of being watched?

This fear of being watched started in primary school where I would think I was on a stage and there was an audience watching me. I'd turn around quickly sometimes to try and catch the audience, but it felt like they were all moving. In secondary school when a group of my 'friends' told me that this girl was obsessed with me, and they had convinced me that she was, and me and this girl used to hang out quite a lot, and when she would leave my house, I used to think she had planted cameras in my room and was watching me. The paranoia grew quite a lot from then on where I would think that other people were watching me and that there were more cameras in my room where my dad was watching me, or my sister was watching me. It got so bad that I couldn't get dressed in my room, that I'd have to go into the bathroom. Sometimes it wasn't just cameras though, sometimes I'd think the ghost of my granddad or the ghost of my mum would be watching me. I still have this paranoia now, I'm just convinced that people I know have put cameras in places and are watching me. For the record, I don't do drugs so it's nothing to do with intoxication. Please help, I don't want to have this paranoia any more :/