What are idiomatic or metaphorical expressions with mole the animal?

Answer 1

The use of the term "mole" to indicate a covert agent does not directly represent an idiom, because it suggests stealthy, unobserved activity.

The mole is used in connection with eyesight, e.g. blind as a mole, but not nearly as often as the totally incorrect "blind as a bat."

The most common metaphor has to do with a mole's burrowing. The phrase "making a mountain out of a molehill" means to exaggerate the effect of an activity or event, referring to the very small amount of dirt a mole leaves on the surface.

Answer 2

1. "To have a molehill out of a mountain": Exaggerating a small issue to seem larger or more significant than it really is.
2. "To play Whack-a-Mole": Trying to solve a problem, but new ones keep appearing in a never-ending cycle.
3. "A mole in the wall": Refers to a hidden observer or spy within a group or organization.