Pen. Code, § 1203.73

The probation officers and deputy probation officers in all counties of the state shall be allowed those necessary incidental expenses incurred in the performance of their duties as required by any law of this state, as may be authorized by a judge of the superior court; and the same shall be a charge upon the county in which the court appointing them has jurisdiction and shall be paid out of the county treasury upon a warrant issued therefor by the county auditor upon the order of the court; provided, however, that in counties in which the probation officer is appointed by the board of supervisors, the expenses shall be authorized by the probation officer and claims therefor shall be audited, allowed and paid in the same manner as other county claims.