dig vs dig in

dig is a noun but dig in is not a noun.

Word	Noun	Adjective	Verb	Adverb
dig	Yes	No	Yes	No
dig in	No	No	Yes	No

dig (noun)	dig in (noun)
the act of digging
the act of touching someone suddenly with your finger or elbow
a small gouge (as in the cover of a book)
an aggressive remark directed at a person like a missile and intended to have a telling effect
the site of an archeological exploration

dig (verb)	dig in (verb)
get the meaning of something	eat heartily
turn up, loosen, or remove earth	occupy a trench or secured area
create by digging
remove the inner part or the core of
poke or thrust abruptly
thrust down or into
remove, harvest, or recover by digging
work hard