It’s not beneficial to underline the words and sentences while reading. You need to use your own words to have an understanding of the material. There are studies that show that students don’t understand if they type with their computers in the lectures. If they write using their hands they understand much more effectively. Because they have to think whether they put something on paper, or not. In this case they can remember even one week later.
While reading nonfiction you need to keep something to take notes on and use your own word. Do not copy the text verbatim from the material you’re reading. Use your own words and tell the content and the gist of it using your own words.
Other forms of note taking is useless.
From: Ahrens - How to Take Smart Notes