This is difficult to do if the probe is purchased.If you use a homemade coaxial cable probe, choose a thicker coaxial cable. From rg-174 to rg-58, or from rg-58 to rg-8.The hardness of thicker coaxial cables makes this approach impractical, but it solves the problem of instrumentation.
Still, you should know what effect a safe ground disconnect has on high-frequency signals.
If the enclosure of the oscilloscope is well isolated from the safety ground wire, the shielding ground loop of the oscilloscope probe will be cut off, thus reducing the shielding current.Unfortunately, disconnecting the safe ground does not provide good isolation.
At frequencies higher than 10MHZ, the oscilloscope has sufficient ground capacitance in any case, so simply disconnecting the safe ground is not effective.