Hunter Hunted (Fallout 4)

Hunter/Hunted is a quest and achievement/trophy in Fallout 4.

Quick walkthrough
Travel to C.I.T, track and kill the courser, and then take his chip.

Detailed walkthrough
Upon getting the quest travel to the C.I.T. Ruins north of Diamond city, the "Courser signal" will be available on the Pip-Boy's radio at that point, tune to it and follow the signal east to Greentech Genetics.

Greentech is filled with Gunners, fight your way up further and further, the Courser is obviously wreaking destruction ahead as a number of scripted fights take place. Eventually on the seventh floor there will be an elevator, take the elevator up.

A couple more levels and the target can be heard threatening some Gunners for a password, approach him and he'll ask what you want, shortly afterwards there will be a fight unless you got the deactivation codes from Mama Murphy. The Courser will use a Stealth Boy during the fight, once it's over take the chip from the Courser and the mission is complete.