Chances are that squeaking has been observed before in weevils, as many other types of beetles do this too, such as longhorn beetles and water beetles. However, I have found nothing about squeaky weevils so I can’t help but wonder if it’s ever been a recorded behavior. Upon close inspection, I’ve found that a weevil (this one in particular at least) produces the sound upon provocation by a larger “predator” by flapping its rearmost bottom abdominal section up and down, which I’m guessing scrapes against something in order to output the friction energy into sound.
For size reference, this weevil was photographed next to a guitar pick