Had you asked this question, I could have told you that, while you can use a musical instrument, no, it’s not a great idea for the instrument or for your cleaning project.
Depending on the amount of junk under your bed, a broom or a rake or possibly a hoe would be the preferred tool.
If you are completely certain that there are no volatile items or things that may contain mold spores, you could take it up a notch and clear out the space under your bed with a leaf blower.
If there are only dust bunnies and pet-hair tumble weeds, a hairdryer will be pretty effective, but we both know you are dealing with more than that under your bed at any given time.
Another possibility would be to move your bed and then–BOOM–all the junk under it is exposed for sorting. Anything that sticks underneath your bed will only get you in trouble, anyway.
At least you didn’t use a trumpet to chase the cats under there and back out again. Wait. Did you? Is that why they’re so bonkers?
Anyhoo, a rainstick really should be able to be used like a stick. Now that it’s broken, I guess we should expect a drought, eh?
At least your room is cleaner. Congratulations!!