SQL Server 2014 Audit

I'm configuring SQL Server Audit to log all INSERT, UPDATE, DELETE, and SELECT operations. I've tested and recorded everything I need (time, action, server principal, server instance, database name, object name, statement). The only thing missing and that I couldn't find is the field that stores the changes before they're modified by UPDATE and DELETE. If someone changes them, I need to know what was stored beforehand. Could someone help me? Thank you.