Yes, CAPTURES is a Scrabble word!

Letter values in Scrabble US: C 3, A 1, P 3, T 1, U 1, R 1, E 1, S 1.

Is it a valid word?

CAPTURES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the act of forcibly dispossessing an owner of property
a process whereby a star or planet holds an object in its gravitational field
any process in which an atomic or nuclear system acquires an additional particle
the act of taking of a person by force
the removal of an opponent's piece from the chess board

succeed in representing or expressing something intangible
attract; cause to be enamored
succeed in catching or seizing, especially after a chase
bring about the capture of an elementary particle or celestial body and causing it enter a new orbit
take possession of by force, as after an invasion
capture as if by hunting, snaring, or trapping

Also: gaining control.