Proper answer to give prospective employer regarding termination from previous employment?

Terminated after 1 year and 8 months from job recently. Now I am trying to find new employment, but not sure what to put on applications as to reason for leaving or to give ok to contact previous employer ? Also, if ever given the chance for an interview, what is proper to say why left previous employment (after just a short time there) or why terminated ? They terminated me with false accusations of “insubordiation” and other false and embellished lies.