Very early in the single player campaign, I saw a hint in one of the loading screens that I can hack enemy Spectres to fight on my side. I faintly remember to have read somewhere that I have to get behind a Spectre (preferably using cloak) and use my data knife, but that never seemed to work.
The only mission I actually managed to hack a Spectre was the mission where you get the Arc tool, which fires electricity and disables Spectres for a moment. Then, when I got behind them, I got a prompt "Press E to hack Spectre" or similar almost every time
However, this didn't work again the following missions. So am I missing something crucial? I'm playing on PC.
I just realized that there are also Stalkers, which can't be hacked. Did I maybe mix those two up and that is the source of my problem?