My cars engine (00 Honda Civic lx D16Y7) is about to go out and my friend is selling me a B16 high compression build engine. My question is?

If you've ever gone from a single cam to a dual overhead cam could you tell the difference in power. Was it noticeable to you when you first got on it. My single cam has always treated me well so I've never had to get another car. Now 4years later the engine is about to give and I'm wandering if I do the swap it it'll actually be worth it. The single cam feels sorta slow in the highway but I've never driven a B series so I'm trying to see if the power is noticeable enough to make the swap fee worth it.

I don't know about Honda, but I do know DOHC engines and can give you a direct comparison.
I have a L4, a 70s Vega block, in a 96 Pontiac Sunfire. It has the optional aluminum head and DOHC. The DOHC has much more torque and HP than a SOHC L4. I've owned both engines in essentially the same car. You will definitely notice the difference.
The DOHC in my Sunfire convertible will hit 105 on an entrance ramp to the freeway from a dead stop and have more left. The SOHC in my Cavalier convertible would hit about 90 and it was hitting red line doing it.
I think you may need the ECM to go with your new engine, but if you want more torque and hp, to me it is worth it.

You would feel the difference when the vtec kicks-in yo.
You would need engine mount, wiring harass, ecm, transmission for the B. For the cost I would get a RSX Type-S for $7000

A 1.6 with a single cam is often rated at about 88 horse power, while a dual overhead cam engine (4 valves per/cylinder) can turn 96 to 110 horse power. That is a 10% gain in general. I strongly recommend making sure you get the ECM and associated electronics to go with the swap. The fuel curves will be different at least and possibly some other parts (air metering system to name one).
Other sized engines had similar differences.