1 Kings 2:39

two of the servants of Shimei Shimei appears to have been a man of wealth, both from this circumstance, and from his ability to establish himself in Jerusalem as soon as Solomon commanded him. The servants may have been Philistines.

Achish son of Maachah king of Gath The Achish to whom David fled on two occasions (1 Samuel 21:10; 1 Samuel 27:2) is called the son of Maoch, which may be only another form of Maachah. But the time which elapsed between David's flight and the death of Shimei makes it doubtful whether the same man was king still. The same royal names were so frequently carried on in alternate generations that the similarity need not surprise us. So Hannibal was the son of Hamilcar, and Hamilcar the son of a former Hannibal.

they told Shimei i.e. Some persons who had come to know of the whereabouts of the servants.