Answer: i believe the answer would be simile.
Explanation: the phrase "like a caged puppy" uses the word like to compare him to a puppy.
"[a simile is] a figure of speech involving the comparison of one thing with another thing of a different kind, used to make a description more emphatic or vivid (e.g., as brave as a lion, crazy like a fox )."
hope this helps! :)
