when we ask a question using 'did' what form of verb will follow ? v1 or v3 example: how did he come ? or how did he came?

(V1) How did he come? is correct. Because did is already in past tense, so no need of another past form (V3).

All the modal verbs (will, would, can, could, may, might...etc) and do forms (do, does, did) are anomalous finites. They always take base form after them. (v1) Will come.. Would come.. May come.. Might come.. Do they/he /she come.. Did they /he/she come..