Green’s Dictionary of Slang

the tapping of a telephone, or other forms of electronic surveillance.

1972		P. Fordham Inside the Und. 82: Unauthorized bugging does go on.
1982		(con. 1969) J. Ehrlichman Witness to Power 158: A report was based on ‘a confidential source’—the Bureau euphemism for wiretapping or bugging.
2008		Guardian 13 Feb. 27: Many questions for the inquiry into the covert bugging.