It is kinda confusing to describe the way a No-Peep works.
I' d first say that the Hind Sight would go between pins & string. When you draw back you will then align the Hind Sight with one of your pins & then line up the appropriate pin to your target. I didn' t like the Hind Sight because I found it flimsy, hanging out in mid-air & easily bumped out of position plus it obstructed the target.

As for the No-Peep, it is like a peep sight or kisser button or what ever else you might use to secure & confirm your anchor point. It sits above or below your sights but lets say " is NOT part of your sight system" , it is part of your ANCHOR system. (Hopefully that makes sense). When you pull back & anchor, you will see the dot within the No-Peep line up within itself. If you are not anchored up correctly or even put the slightest bit of torque on the bow, the dot will not be centered properly. So what it does, is make you confirm your anchor. I use my 2nd. knuckle of my index finger to the back of my jaw bone & trigger my release with my middle finger. The slightest bit off & the No-Peep is not aligned. Don' t think of it as a " bubble" either. Again, it only confirms an anchor like a peep yet you cannot creep or torque.
John