Boyd’s Bible Dictionary:

(head). Title for a leader of a band of ten, fifty, hundred or thousand (Deut. 1:15; Josh. 10:24; Judg. 11:6,11). Also a civic meaning (Isa. 1:10; 3:3). “Captain of the Guard” (Acts 28:16), was commander of the Praetorian troop of Rome. “Captain of the Temple” (Acts 4:1), was chief of the Temple watchmen.

Concise Bible Dictionary:

In the Old Testament this word is used for one filling any office of rule or command: as the head of a tribe (Num. 2:3-29); commander of an army, and so forth. The person who appeared to Joshua as “a man” declared himself to be “captain of the Lord’s host.” He told Joshua to remove his shoes from his feet, for the ground was holy, evincing that he was God’s representative to lead their warfare (Josh. 5:14-15). In the New Testament the Lord is called “Captain” of our salvation, ἀρχηγός, “chief leader” (Heb. 2:10).
There was also a “CAPTAIN OF THE TEMPLE,” στρατηγός (Luke 22:4, 52; Acts 4:1; Acts 5:24, 26). This word is literally “the leader of an army”; it is also applied to magistrates (Acts 16:20), but the captain of the temple was set not over the soldiers, but over the priests and Levites: (Compare Num. 32; 1 Chron. 9:11; Jer. 20:1).
THE CHIEF CAPTAIN or HIGH CAPTAIN is χιλίαρχος, lit. “Captain of a thousand,” applied to the chief of the soldiers in Jerusalem (Acts 21-25).
CAPTAIN OF THE GUARD (Acts 28:16), is στρατοπεδάρχης, properly “commander of a camp,” but here the prefect of the Prætorian Guard, an officer to whom state prisoners were entrusted at Rome.