2004 Camry: I got a clicking/crackle noise by engine area, what is it?

My sister's 2004 Camry is starting to make this mixture noise of clicking & crackle noise when I turn the engine, while the engine is on & when I accelerate. I open the hood and the noise seems like it's coming between the timing belt and compressor. What is it and do I need to buy a part to fix it or what? I have 112,000 miles on the car too.