The invention relates to an ultrasonic measuring unit for attaching to a measuring instrument. The measuring instrument is designed in such a way that the measuring instrument can be arranged on a movement axis of a machine. When the ultrasonic measuring unit is arranged on the measuring instrument, an ultrasonic measurement can be carried out by means of the ultrasonic measuring unit. The ultrasonic measuring unit comprises a tubular sleeve and an elastic carrier element. The tubular sleeve surrounds the elastic carrier element. The elastic carrier element consists of a material that conducts ultrasonic waves. At a first end of the tubular sleeve, the elastic carrier element protrudes beyond an outer edge of the tubular sleeve. The tubular sleeve and the elastic carrier element are intended to contact, in particular directly, the surface to be measured, during a probing process of the measuring instrument.