Can be a few things. I found most times, no lie, most times after a FREE tune up from the shop, I get the bike back and there is a tick in one of the wheels. Reason is they true the wheel and don't pay attention to whether or not they are binding the spokes when they turn the nipples. I place a black dot on my spokes with a marker and when I twist my nipples, I make sure the spoke does not spin as well. Must be a clean turn onto the spoke threads or it will bind. I started building and maintaining my own wheels after 11 bike purchases and terrible service. Most shop guys are not wheel guys. So if you've had it in for a tune up lately, that could be the problem.
If not, it could be the spokes have lost tension and need to be re adjusted. If left loose, they acquire some play and allowed to move, soon they will snap like a hanger wire that keeps getting bent over and over, eventually snaps. So make sure the wheel has proper tension. And if you do start twisting nipples, make sure to monitor the spokes don't turn as well.
Some rims have eyelets like mavic open pro. That drove me crazy in the past as the eyelets work loose and creak like crazy. I haven't used those rims for 20 years because of it.
Also, I had a creak, every revolution one time after I replaced a rear tube. Somehow, the cassette ring worked loose and made noise while pedaling. Took me a couple of days to remember that I had repaired a flat. So I took it off, checked the ring, tightened it and boom, no more creak!
That's about all I got. 😄
