How I can monitor SQL Server 2012 databases to determine the security privileges that are called by different processes Is there any tool that can identify the SQL privileges or roles that are being called on query by query basis. We need to know which ones are being used at each time on a Microsoft SQL Server 2012.
You can use SQL Activity Monitor. This will show the current queries executing in your SQL Server instance with below details


SPID
Login
Database Name
Task State
Command
Application
Wait time
Host Name and many more under PROCESSES tab


Also you can have a look on


Resource waits
Data File I/O 
Recent Expensive Queries