How To Secure Sql-Server Database From Intended Manipulation by IT mans or Database Admins or System Admins
Sure, this is what compliance auditing solutions like IBM Guardium and Imperva do. They're appliances that sit in between your SQL Server and the rest of the network, and they capture everything that happens without affecting end user activities.

They're expensive - think six figures and up for the full implementation, and it's not going to be discreet.

If you were looking for something free or cheap, you can try using the built-in auditing features in SQL Server, or software products like Idera Compliance Manager, but be aware that sysadmins can disable those tools (because they're likely gonna be the ones installing them anyway.)