In Ant-Man, Hank Pym sends Ant-Man
to the Avengers facility to steal technology needed for the raid on the Pym Tech facility. The small device is then added to the Pym network, arguably to distract the company from the upcoming sabotage. But then later we see the entire Pym building implode into what we might imagine to be the location of the device that was stolen from the Avengers facility.
So what did Ant-Man steal from the Avengers? And what does it do?