The USB 2.0 specs requires a differential impedance of 90 Ohms and a common mode impedance of 30 Ohms +/-%.
This, by definition, gives a target of an odd mode impedance of 45 Ohms and an even mode of 60 Ohms.
The USB should be terminated locally and the signal will be >20 MHz so HF test & measurement techniques are critical.
You ought to use a high speed Differential FET Probe ( 1Gohm || 1 pF) but these Rhode & Schwarz or TEK probes are expensive ($$$).
The next best budget method is to use two 10:1 probes rated for 200MHz+ calibrated with spring probe adapters to pin sockets near signal source.
You can even twist the two probe cables for better HF CMRR. These common springs eliminate ground clip wire and expected coax resonance and pulse ringing from ground clip ESL+ coax C. It uses the exposed probe pin (with clip removed) with a ground spring coil tip around the barrel of the probe.
If designing your PCB, it is useful for DFT reasons to add PTH holes for this test method for differential probes. If not, use the nearest pads to the signals.
Calibrate each probe with a perfect square wave, then calibrate both probes on the same signal using DSO Ch. A-B or 1-2 to get a "flat line" up to max frequency. Now you have a decent Diff. Probe setup. using 2 probes. This is Ok for the slower speeds of USB2.
A common problem with USB is when one end uses a floating SMPS portable to another DC powered device with PE grounding. Then the SMPS noise becomes a large interference to USB signal integrity and challenges the CMRR of signal from passive unbalanced wires and traces. (Often connecting the mobile SMPS to PE gnd. shunts this interference and prevents connection errors.) The floating SMPS supplies have feedthru C in the transformers which inject a large CM noise signal. Sometimes the CM chokes used are ineffective depending on the spectrum.