The invention relates to a measuring probe for non-destructive measuring of the thickness of thin layers, in particular in cavities, which are accessible by an opening or on curved surfaces, with a measuring head, which comprises at least one sensor element and at least one contact spherical cap, assigned to the sensor element on a surface, to be checked, of the cavity, and with a gripping element for positioning and guiding the measuring probe on and/or along the surface to be measured, wherein on the gripping element, a long, elastically yielding guide bar is provided, which accepts the at least one measuring head on its end opposing the gripping element, in such a way that it is moveable with at least one degree of freedom in relation to the guide bar.