(Hidden) Malware Data Usage

As I was wondering how much data malware that's sending screenshots, audio, and/or photos would use, I began monitoring how much data my iPad and my iPhone are sending with the help of several apps.

Just now, after slightly more than half an hour, only 1.6 MB have supposedly been sent, with around 11 MB having been received. Could someone make an educated guess as for what could be done with 1.6 MB in slightly more than half an hour in relation to screenshots, audio, and/or photos? And could the real data usage (should it exceed 1.6 MB) be hidden from those network monitoring apps?