The Stimpack can be used to heal instantly whenever you get injured or hurt during combat. Quite surprisingly, it will not harm you or shoot you down. Just activate the robot by talking to it.
At this location, you will encounter a large Combat Sentry Prototype MKIV that is roaming around or standing still at some point.Just head over to the Robotics Disposal Ground, which is located right next to the Sanctuary and Red Rocket Gas Station in your in-game mini-map.It must be noted that the companions available in the game are not as formidable as the sentry-bot follower and hence it is imperative that you try unlocking this special ability quite early into the game.
