An ultrasound probe in combination with at least an operating unit such as a tracking sensor or receiver and/or a keypad and/or a surgical tool support, the probe and the at least one operating unit being each one provided with one of two parts of a releasable joint, the said two parts of the joint being releasably engageable one with the other by magnetic force and by mechanical coupling characterized in that the probe has a case, the case comprising a case wall, the part of the joint on the probe comprising a layer of magnetic insulating material having a predetermined dimension and shape the layer is laid over the surface of the case wall facing the interior of the probe, one or more magnetic elements being distributed according to a predefined pattern between the layer of magnetic insulating material and the wall of the case of the probe; the said part of the joint associated to the one or more operating units comprises a socket provided with a contact surface facing the external surface of the wall of the case of the probe and coincident with an internal layer of magnetic insulating material and the magnetic elements, the said contact surface being covered with a magnetic insulating material and the said layer of magnetic insulating material bearing on the side facing the probe one or more magnetic elements which are positioned and polarized in a way as to interact in an attracting manner with the pattern of one or more magnetic elements on the probe; the mechanical coupling is provided between the two parts of joint associated to the probe and to the one or more operating units, the said mechanical coupling consisting of an indentation having a predefined depth on the probe, in a region coinciding at least partly with the distribution of the magnetic elements and corresponding to at least part of the height of the socket of the part of the joint supporting the one or more operating units and having a predefined shape and dimensions along the external surface of the case of the probe, the socket having a corresponding shape with dimensions equal or slightly smaller than the ones of the indentation. the probe has a case, the case comprising a case wall, the part of the joint on the probe comprising a layer of magnetic insulating material having a predetermined dimension and shape the layer is laid over the surface of the case wall facing the interior of the probe, one or more magnetic elements being distributed according to a predefined pattern between the layer of magnetic insulating material and the wall of the case of the probe; the said part of the joint associated to the one or more operating units comprises a socket provided with a contact surface facing the external surface of the wall of the case of the probe and coincident with an internal layer of magnetic insulating material and the magnetic elements, the said contact surface being covered with a magnetic insulating material and the said layer of magnetic insulating material bearing on the side facing the probe one or more magnetic elements which are positioned and polarized in a way as to interact in an attracting manner with the pattern of one or more magnetic elements on the probe; the mechanical coupling is provided between the two parts of joint associated to the probe and to the one or more operating units, the said mechanical coupling consisting of an indentation having a predefined depth on the probe, in a region coinciding at least partly with the distribution of the magnetic elements and corresponding to at least part of the height of the socket of the part of the joint supporting the one or more operating units and having a predefined shape and dimensions along the external surface of the case of the probe, the socket having a corresponding shape with dimensions equal or slightly smaller than the ones of the indentation.