A constable; a law officer whose business it was to apprehend criminals. Pole or poll means head, person; and the word means one who catches persons by the poll or neck. This was done by means of an instrument something like a shepherd's crook.
“Cacchepoles, from catch and pole, because these officers lay hold of a man's neck.” —Wiclif: New Testament (Acts xvi., Glossary).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894