The invention relates to a system and a method for the detection of target components (102) in a sample with the help of indicator particles (101) distributed in said sample. The distance (d) between indicator particles (101) and a contact surface (112) is determined after the target components could bind to the contact surface and/or the indicator particles. Thus it is possible to detect how many target components (102) are bound without a need for a binding between indicator particles (101) and contact surface (112). Optionally the indicator particles (101) can be affected by a modulated force, e.g. via an electromagnet (141). The determination of the distance (d) between indicator particles (101) and contact surface (112) may for example be achieved by frustrated total internal reflection, measurement of magnetic fields, or FRET.