Captain's Hook
Artifact — Equipment
Equipped creature gets +2/+0, has menace, and is a Pirate in addition to its other creature types.
Whenever this Equipment becomes unattached from a permanent, destroy that permanent.
Equip 
Sara Winters
Rivals of Ixalan (RIX)
• #177Rulings
Captain's Hook becomes unattached from the creature it's equipping if you equip it to a new creature, if Captain's Hook leaves the battlefield, if the equipped creature ceases to be a creature, or if Captain's Hook ceases to be an Equipment. (It also becomes unattached if the equipped creature leaves the battlefield, but the triggered ability won't do anything in that case.)
(wotc • 2018-01-19)
Rulings
Captain's Hook becomes unattached from the creature it's equipping if you equip it to a new creature, if Captain's Hook leaves the battlefield, if the equipped creature ceases to be a creature, or if Captain's Hook ceases to be an Equipment. (It also becomes unattached if the equipped creature leaves the battlefield, but the triggered ability won't do anything in that case.)
(wotc • 2018-01-19)