How do make both your posted pic and profile pic on facebook get the same likes and comments?

Ok so I've seen people post pics and have that same pic as their profile pic, but if someone likes it, both the posted pic and the profile pic gets liked by that person. Same goes for if someone comments on that pic. How do you do that? I tried posting the pic then making it my profile picture(i clicked on the posted pic then there was an option of making it your profile pic, thats how i did it) after but only my posted pic got the likes and comments not my profile picture (they're the same pic by the way). Also the caption I used for my posted pic did not appear on my profile pic. Oh and all my pictures can only be seen by my friends. So is there any way to connect a posted pic and your profile pic so both of them get the same likes and comments? Cause I've seen other people do that....