Discovery of topological matter has triggered an intense research work motivated by the emergence of promising features among which the existence of helical ballistic edge states. For 2D systems or 3D high order topological insulators, they form one dimensional conducting channels on the edges with two time-reversed spin-momentum-locked states which do not backscatter. Using our newly developped ultrasensitive GMR-based (Giant Magnetoresistance) magnetic field sensor, we plan to detect the supercurrent carried by the helical edge states as well as its fluctuations at equilibrium, which are predicted to contain clear signature of the relaxation mechanism and topological protection.