Getting Way To Smart

So tonight I put Braxton in his crib for a short time-out, because he kept climbing on the pack-and-play. I was in the restroom, and heard him say "hi." I looked out the door and he had crawled out of his crib, without me hearing him. He is getting way to smart. I dont know what I am going to do if he keeps doing it. I guess we will have to deal with it when we get there. Any ideas?