An arrangement for carrying out dynamic magnetic field measurements in a MR imaging or MR spectroscopy apparatus comprises at least one magnetic field probe (2) comprising a MR active substance (4), means (8, 10) for pulsed MR excitation of said substance and means (8, 10) for receiving an MR signal generated by said substance. The magnetic field probe further comprises a radio frequency shield (12) against external high-frequency electromagnetic field irradiation substantially surrounding the magnetic field probe. The shield is composed of conductive elements embedded in a dielectric material. The conductive elements are electrically conductive filaments and/or electrically conductive platelets.