i have had a lot of variations of this throughout my lifetime.

some was feeling like i was being watched from the outside (as a child, it was eyes in the walls at one point or times kids did watch me in different situations and thought it was funny) or a feeling of being watched from above (like a higher power type thing due to something i was told/overheard as a child) or being watched from the inside which is more related to the alters/parts.

then there is the usual fear/paranoia type of being watched and potentially being followed/hurt (but some of that was reality too in the past).

there are a lot of variations of it for me, so it is a mix of PTSD, DID, and other things that all co-exist and the effects of it all depending on which is the prominent one (or sometimes all at the same time).