Hi,
I am not sure I understand the scope of your inquiry.
Since control group recipients are excluded form a delivery, they will not receive any campaign messages, so there is no direct tracking that can be done for that population.
What you can do, is to identify the excluded population by setting up delivery logs query with status = Ignored and controlGroupMember = Yes, and determine if that population did or did not perform similarly with the targeted campaign population.
Hope this helps,
Ionut