hi,
first off, i do not have a out of the box solution for you, but maybe help in your search.
the way the circuit works is by measuring the voltage drop across a precise resistor which is in series with the load and then, using essentially ohms law, convert the voltage drop to current. the resistor is often referred to as shunt resistor. this is how multimeters do current measurements as well.
the op amps like they are used in the circuit do pretty much the same thing, but they also give the voltage dropped across the resistor back to the circuit. that's why they are connected to the 5V line as well.
this video gives not a bad explanation on the subject Precision Low Current Measurement w/ Feedback Ammeter - YouTube
it should be possible to measure uAmps.