haha. i hate to suggest it… but are you sure it’s not a small mouse?
in all seriousness its probably one of drobos fans… however…
as you will notice from my avatar, i keep reptiles… most domesticed reptiles eat crickets:
very often one or two will “escape” at feeding time - but i’ll just catch it later (when it make the mistake of walking across the lounge) and then chuck it in with the dragons and thats the end of him.
sometimes… if i don’t manage to recapture them… the cricket like to go places warm and dark… i.e. inside electronics…
inside my subwoofer is a particular favourite. and they sit in there "chirrup"ing until it drives me mad
so do check for mice, but its probably a fan!