I gained a pound

You didn't gain muscle in a week - it's very difficult to gain actual muscle (especially for women, and especially when eating at a calorie deficit).

Your muscles are retaining fluid. When you exercise, you are actually tearing the fibers in your muscles. That makes your muscles retain fluid to repair themselves. Totally normal. If you take a rest day or two and drink lots of water, that number will go down.

You didn't gain fat unless you ate 3500 calories over your TDEE. Which probably didn't happen unless you had a lot of really, really, really bad binges - and I'm guessing you didn't.

Keep doing what you are doing and just look for the general downward trend on the scale. You can expect the scale to fluctuate a lot.....I can fluctuate 5lbs in one day. But as long as the number is going down in general, that's all I worry about.

I am hoping that I have gained muscles and not weight.

Previous poster's answer is correct, but I'd like to add: I think you mean "I am hoping that I have gained muscles and not fat." Muscles are actually part of your weight.