[EE] measuring the magnetic field from a small trace carrying a < 50uA load?

When developing battery powered devices, sometimes it can be difficult to
track down where the last few dozen microamps of load are being drawn.

One can resort to systematically cutting traces and desoldering components.
But that is destructive, labor intensive, and error prone.

I would like to know if an active probe exists that can measure and
discriminate the current/DC magnetic field of small < 50uA loads on small
but loosely packed PCB traces.

Are there other viable (hopefully nondestructive) ways to track down small
loads? (A low noise thermal camera in a vacuum chamber?)

-- 
Jason White