Can my iMessages be seen through the carrier company like sprint

They can't see the message and they don't know who you're messaging. All they can see is that you're using data.

It's like your electric company knows you're using electricity but they don't know whether you're using it to power your clothes dryer or your television.

As far as the carrier is concerned, iMessages are data, just like streaming music, downloading email. They don't see the content of the messages or any information on when or to whom they are sent.