Is uncover a compound noun

No, the Word 'uncover' is a verb (uncover, uncovers, uncovering, uncovered); meaning to remove a cover or hat; to reveal or disclose.

example: An investigation should uncover the truth.

The verb 'uncover' is not a compound Word; the verb is made up of the verb to 'cover' and the prefix 'un-' (the prefix is not a Word).