How to get electronic sensors in Modern Warfare 4 DMZ

In Modern Warfare 4's DMZ mode you need electronic sensors to upgrade your starting stash, which fills up after the first couple of matches. The best spots are inside buildings, especially apartments, and inside computers; one run south along the road in Hanrim Village in the north yielded all ten needed. Bring a blue medium backpack so you can secure-slot what you find and still progress the upgrade even without exfilling.