someone made a contest about finding a hidden signed Tx
and also he give us a Hash
i mean can i extract a private key from this info
there is just not enough information in your comments to give you "the answer" you are looking for. usually these "puzzles" are more complicated than that. the hash that you have can be anything! maybe it is hash of a link containing further instructions. maybe it is hash of a transaction that has an OP_Return with the next step in it!
or maybe what you are calling "hash" is a hex and that IS the private key but that sounds too simple!
example: 0C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D is the private key of 1GAehh7TsJAHuUAeKZcXf5CnwuGuGgyX2S (
https://en.bitcoin.it/wiki/Wallet_import_format)