You can use gesture functions with your fingers or Apple Pencil. Gesture functions let you handling documents more simple way.
You can capture a document, draw underline, highlight text, and etc. use gestures. 

• Underline Gesture
• Round Bracket Gesture
• Long-press Gesture
• Box Gesture
• Circle Gesture
• ‘L’ Gesture
• Eraser Gesture
• Drag & Drop
• Flip Pages
• Two-finger Pinch
• Open/Close Pop-up document
• Pen Gestures on Notes
• Undo/Redo Gesture