System (18) to localize a micro-device inside a target body part (10), comprising: a micro-device remotely steered and controlled from outside the target body part (10), a control unit (20) comprising a memory (28) for storing one ultrasound image (29) of the target body part (10), one probe (22) being brought in contact with a securing body part (24) of the patient, at least one tracker connected to the micro-device, wherein the probe (22) and the tracker communicate with ultrasounds, the control unit (20) being thus able to localize, in real time, the tracker within an internal referential (R) defined with regards to the probe (22), wherein the control unit (20) displays, on a screen (30), the ultrasound image (29) and displays, in real time, the localization of the micro-device on the ultrasound image (29).