Auxiliary verbs (derived from helping): Do, have, could, ought to, need, be, etc.
Modals: those pre-mentioned in the above group (need, ought, could) and moreover: can, must, will, would, might, may and so on.
Must is one of the modal verbs hence we do not use any other auxiliary verb for creating a question. We just invert the word order.
EG.: I must pass my exam.
Must you pass your exam?
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