A symbol that represents "busy"? [on hold]

I'm working on something fairly trivial at the moment, just a custom prompt for my terminal (which looks like this so far).

I'd like the prompt to indicate whether there are any jobs running in the background, and am wondering if there's a more suitable character/symbol I can use than what I'm currently using, the emoji ⚙️

In short, are there any glyphs that convey the meaning "working on something"?