Don't ask them to point to this or that. Pointing doesn't require them to verbalize. Don't ask yes or no questions. Yes or no questions do not require them to use their vocabulary. When they do answer, repeat what they said and expand on that topic. Dialogic Reading builds vocabulary, comprehension skills, understanding of sequencing in a story and more!
Children who have been read to dialogically are substantially ahead of children who have been read to traditionally on tests of language development. Children can jump ahead by several months in just a few weeks of dialogic reading. Dr. Grover Whitehurst
Books with few words or simple stories work best for Dialogic Reading. Books that your child is interested in naturally and have pictures in them with objects they are familiar with work well. Rhyming books or books that are too long, are not the best choices. Try wordless books too!
But don't think you have to do this all the time. Of course, it's nice for you and your child to just read a story from start to finish.