Learn English – Which word should I use to describe the noise made by an electronic device

It's a "stormy petrel." The idea, as described on the linked page, is that (for example) you never (or, at least, rarely) find a petrel that's not stormy. Similarly, "all shrift is short," and lots of other examples. One of the ones there is in fact "every skirl is of bagpipes."

This is a tricky one to come up with one apt word without getting into various connotations:

• A moan is a low sound, generally.
• A whimper sounds plaintive or submissive.
• A grunt or a groan doesn't sound ladylike.
• A squeal sounds too drawn out.

I would be surprised if there's actually a definitive word for it. To describe the sound in that context, I might say squeak, which is a sort of cute sound.