A district court of the United States shall appoint qualified persons to serve, with or without compensation, as probation officers within the jurisdiction and under the direction of the court making the appointment. A person appointed as a probation officer in one district may serve in another district with the consent of the appointing court and the court in the other district. The appointing court may, for cause, remove a probation officer appointed to serve with compensation, and may, in its discretion, remove a probation officer appointed to serve without compensation.