The mini-lathe was not equipped with a scale measuring the spindle depth. Probably the cheapest solution is a PVC caliper for 0,5 Eur.
Caliper was cut as shown in the picture. The end of the main scale was used for fixation of the zero. M 4 hole was drilled and tapped to the tailstock. Using a screw the vernier is fastened to the desired position. Part of the vernier was glued to the tailstock to help keeping the main scale in the direction of the movement.