Marvel's The Punisher: 31 Easter Eggs & References You Need To See
24. Micro
David "Microchip" Lieberman was first mentioned back in Daredevil Season 2, whose last episode sees Punisher recover a hidden disc with “Micro” written on it. He's traditionally Punisher's sidekick and provides him with weapon and tech. Even before that, he was also mentioned on Agents of SHIELD when Skye refers to a hacker contact of hers - a full three years before he appeared.
The character debuted in The Punisher #4 by Mike Baron and Klaus Janson and isn't all that recognisable in the screen version, who feels like he's based far more on Edward Snowden. He's an NSA analyst in hiding because of what he knows about Kandahar.
He also seems to know about the fate of other superheroes in New York as he says "You're not the only ghost in New York" at one point. A reference to Daredevil not actually being dead at the end of The Defenders perhaps?