Or maybe "...the rook took the mouse by the proboscis..."?
(If the rook has a proboscis, then the rook takes the mouse "with the proboscis". If the mouse has a proboscis, then the rook takes the mouse "by the proboscis". Compare: "The cat grabbed the frog by the leg, with her teeth.")
But I assume that за хобот means that the хобот belongs to the mouse, not the rook.
P.S. For John Douglas, the word хобот most commonly means the "trunk" of a слон ("elephant").