The answer is definitely a Verb
i mean think about it, "banging" is a loud sound and the main meaning of verb is something like hear, become, happen, or a action. Plus, the sentence says "where is that "banging" noise coming from"
So obviously, its something they heard, IF it were a noun it would probably be a place, thing, person.
But overall, the answer is Verb. Hope this answers your question!