  We investigate the possibility to employ magnetic Josephson junctions as
magnetic-noise detectors. To illustrate our idea, we consider a system
consisting of a quantum dot coupled to superconducting leads in the presence of
an external magnetic field. Under appropriate assumptions, we relate the noise
in the Josephson current to magnetization noise. At the magnetic field driven
$0-\pi$ transition the junction sensitivity as magnetic noise detector is
strongly enhanced and it diverges in the zero temperature limit. Moreover, we
demonstrate that, if also dot energy is affected by fluctuations, only the
magnetic noise channel contributes to Josephson current noise response when the
quantum dot is tuned in resonance with superconducting leads.
