You might want to contact the telephone company.
Utilities and railroads purchased easements for this purposes decades ago in may localities.
Otherwise you may need to take him to court and seek an injunction to stop him.
If he's completed his work, you'll still need to go to court and sue him.
You might try calling the police agency that controls your area. They might intervene under the guise of keeping the peace.
Otherwise, speak with a lawyer. Or, get ready to play lawyer for yourself.