A measurement device for measuring disruptions in a controlled magnetic field comprising: at least one electrode consisting of a sole conductive element surrounded by the controlled magnetic field generated by the device; a controlled magnetic field sensor connected in a closed loop circuit to the at least one electrode, the sensor comprising: an oscillator comprising an active element, the oscillator being coupled to the at least one electrode, a digital module; and a processor connected to the digital module; wherein the oscillator is connected to a transformer (L1, L2) whose secondary winding is connected to the at least one electrode and whose primary winding is connected to the active element of the oscillator; and the oscillator further comprises a polarisation network (R BIAS, V BIAS) configured to polarise, at least, one input transistor (M IN) of the active element of the oscillator; wherein, furthermore, the signal generated by the active element of the oscillator generates a controlled magnetic field in the at least one electrode and this same signal is fed to the input (M IN) of the active element of the oscillator through a feedback network (R F, C F); and wherein the same signal that is applied to the input (M IN) of the active element of the oscillator is processed digitally, in the digital module, such as to be acquired by the processor. at least one electrode consisting of a sole conductive element surrounded by the controlled magnetic field generated by the device; a controlled magnetic field sensor connected in a closed loop circuit to the at least one electrode, the sensor comprising: an oscillator comprising an active element, the oscillator being coupled to the at least one electrode, a digital module; and a processor connected to the digital module; wherein the oscillator is connected to a transformer (L1, L2) whose secondary winding is connected to the at least one electrode and whose primary winding is connected to the active element of the oscillator; and the oscillator further comprises a polarisation network (R BIAS, V BIAS) configured to polarise, at least, one input transistor (M IN) of the active element of the oscillator; an oscillator comprising an active element, the oscillator being coupled to the at least one electrode, a digital module; and a processor connected to the digital module; wherein the oscillator is connected to a transformer (L1, L2) whose secondary winding is connected to the at least one electrode and whose primary winding is connected to the active element of the oscillator; and the oscillator further comprises a polarisation network (R BIAS, V BIAS) configured to polarise, at least, one input transistor (M IN) of the active element of the oscillator; wherein, furthermore, the signal generated by the active element of the oscillator generates a controlled magnetic field in the at least one electrode and this same signal is fed to the input (M IN) of the active element of the oscillator through a feedback network (R F, C F); and wherein the same signal that is applied to the input (M IN) of the active element of the oscillator is processed digitally, in the digital module, such as to be acquired by the processor.