Maxwell Equations and magnetic field?
For a simple example take the capacitor. Current through the capacitor (at all times) is: -

Capacitance \$\times\$ rate of change of voltage across its plates (or \$C\cdot \dfrac{dv}{dt}\$). 

The current begins as conventional charge-movement current flowing into and out of both plates and, in between the plates, it is a displacement current because electrons don't flow through an insulator.

Both currents are of equal value and, if the shape of the capacitor was small relative to some idealized and remote closed-loop, you wouldn't be able to tell if it were just normal old-fashioned charge flow or displacement current.