In my experience working with SmartNet, it all depends on how the items weee purchased, is: together with a codec or separate. The camera could be covered under the codec's serial number if purchased as a bundle or if the camera was purchased separately, than it would be covered under its own serial number. 

The microphone is covered under the codec's serial as it's a minor part to the codec, again this all depends on how these items were purchased to behind with.

You should reach out to a local Cisco partner, they should be able to help with SmartNet and making sure everything is covered like you want.