You can try the "poor man's" differential probe. You use two identical probes a 2+ channel scope with a A-B (or Ch1-Ch2) trace. This is cheap/free but surprisingly tricky to get right.
You must adjust the probes for best CMRR. This is done by first connecting them both to the cal signal square wave, and adjusting compensation on each individually (using individual channel waveforms). Then enable the A-B trace, and if necessary adjust the gain on one channel ("VAR" vertical) to match the other, then adjust adjust the compensation on only one of them to minimize the displayed waveform.
To use this probe, you connect the two ground clips to a common ground point on the DUT, then use use the two probe tips to take a differential reading. Also note that although the differential signal may be small, the vertical or V/DIV setting must be set appropriately for the individual signals w.r.t. ground. The differential signal of interest may be small compared to the large common mode component. You can't just set the V/DIV higher to make the differential (A-B) signal bigger. To set the vertical or V/DIV correctly, enable the A, B, and A-B (or Ch1, Ch2 and Ch1+Ch2) traces, connect across the component(s) to measure, adjust the vertical so that the A and B signals do not saturate/exceed the display, then you can turn those traces off and view only the A-B trace. Every time you change vertical, you must change both channels to match each other, and you may need to slightly tweak the variable gain on one channel to minimize the common mode junk.
All good analog scopes and some older digital scopes did this summation in the analog domain. All newer digital scopes can do the summation digitally via the math function.