Read the first stanza and think.
(i) Is Macavity a cat really?
(ii) If not, who can Macavity be?
(i) No, Macavity is not a cat. The poet has cleverly drawn the elements of a super criminal in the form of a cat. The cat is just a symbolic representation of the master mind criminal.
(ii) Macavity can be a criminal, a thief, or a dangerous person. The cat is used to represent that ferocious and clever criminal.