NOTE: french is my mother language, it's why I can respond.
But english is NOT, so apologies in advance for this aspect :-)
Although previous answers are correct, it seems important to mention something else.
There is a difference between two kinds of verbs, natively rather appropriated for designate either an action/event (what is currently happening) or a result/situation (what is the state due to a previous action/event).
In the case of capturer, which belongs to the first kind above, il a été capturé is the most natural way to use it: it describes an event which already happened (and the result is something like il est prisonnier).
At the opposite, il est capturé may be rarely used: only in a special way to tell the story, where tense is always présent de l'indicatif, often for a dramatical effect.
Example for the "whole" story: Il est poursuivi. Il tombe, il se relève... Mais il est rattrapé: ça y est, il est capturé !