What if when i choose friendly unit with baited hook my baited hpok get destroyed

The ability still resolves in full — destroying the Baited Hook gear doesn't stop it.

Once you activate it, the ability sits on the chain as its own object, independent of its source (Rule 151.2.a.1: it "behaves, once activated, like a spell without an associated card"; abilities and their sources are separate objects per Rule 355.9.c). Killing the gear afterward doesn't counter the ability, and your paid costs aren't refunded (Rule 425.1.c). Since Baited Hook's text never references the gear itself (no "here" or "my"), you still kill the chosen friendly unit, look at the top 5, and may play a unit with Might up to 1 more than the killed unit.

Only an actual Counter effect aimed at the ability on the chain would stop it. Note that killing the gear does differ from killing the targeted unit — if the unit is gone, its Might is null and you reveal 5 but play nothing.