Of course the realisation of Huh? does differ by language; in the Mediterranean, for example, it is E? But the general idea is a mid vowel (as close to a schwa as your language allows), with a questioning tone.
I’ll note anecdotally that the Greek for Ouch! is ox! or ax!—but that because of cartoons, Greek kids now spontaneously say ouch! (I heard my young cousins do it twenty years ago.) Even though /tʃ/ is not even a phoneme of standard Greek. So short expletives, discomfitingly, can be borrowed between languages, just as everything else can.