Question

What 3 molecules that aren't DNA helps us learn about evolution?

Answer 1

We know, DNA is the main molecule by which scientists can learn about evolution by comparing the DNA structure between two different organisms. 
But, in addition to DNA (which is most helpful & important) still, there are 3 molecules that can help us, They are:

1) RNA : - It is found in cytoplasm, as DNA transfers it's codes into RNA during Central dogma, it can help us in evolution studies.

2) Proteins: - Another helpful feature, into which RNA transforms in Central Dogma.

3) Pseudogenes: - It is also known as "Non-coding DNA" It is extra DNA in a genome that do not get transcribed into RNA to synthesize proteins. They can also help us in Evolutionary studies.

Hope this helps!