The baggage is checked pretty carefully, especially in the home port. If you attempt to bring booze onboard, more than likely you will be caught.
I had security hold my bag in my last cruise. I had put Listerine in a water bottle (it was smaller and easier to pack). I had to go down to security and open it for them to smell to ensure it wasn't booze. They let me keep it, but they also showed their huge pile of confiscated Listerine bottles that were filled with liquid that wasn't Listerine!
My advise is to bite the bullet and just pay for your drinks onboard...think of it as part of the ticket price of the cruise.