How do you make a beeping noise when close to enemy? And how do you make it repeat faster the closer it is?

Hi mate you could try:
1. Check the distance between the two GameObjects
2. Add a sound source to the camera (you could make it looping on the component itself or via code)
3. Upon the distance going below a value trigger the sound source (your beeping) to play
4. Use the distance value to set the audio source pitch (which which change the pitch & playback speed of your sound effect, I'm not sure how to just change the tempo so the pitch is the same)
Hope this helps =D