A micromagnetometry system for detecting the presence of very small quantities of magnetic particles comprises a first magnetic hybrid AMR/PHR multiring sensor using a Wheastone bridge electrical configuration, a first current source, a first voltage measurement device, a set of at least one magnetic particles deposited on the first magnetic sensor and a processing unit for detecting from a set of different measured differential voltages a magnetic flux shift representative of the presence of a least one deposited magnetic particle.The micromagnetometry system comprises means for creating a magnetic excitation field HAC to make produce by each motionless magnetic particle a stray magnetic field oscillating along the time at a constant frequency ω ranging from 10 Hz to 3 KHz.