Narcissists crave you. When you abandon the narcissist, hacking and stalking is usually the result. When the narcissist hacks all your phones, computers, routers, etc, this gives them the leverage to control your mind.
Some examples of the various ways a narcissist will attempt to control their victim is to attack their social media as random aliases, entrenching it all with pop up advertisements that speak to their victim’s insecurities. The narcissist than uses his victims reactions, as supply and faulty proof that their victim is paranoid and crazy.