The problem...

The standard method for calibrating a 10x probe is by measuring a square wave provided by the oscilloscope, and adjusting the trim-cap until all overshoot and undershoot is eliminated. This ensures the accuracy of the probe over a large bandwidth, but the accuracy at any specific frequency may have a degree of error which is unknown.

How can you address this?

Most of time, we are only interested in certain frequencies, especially for resonance devices. In that case, you can measure a sine wave signal from a function generator at the desired frequency with a 1x probe and a 10x probe. You can adjust the 10x probe's trim-cap until the two signals have the same amplitude.

Now, you have calibrated your 10x probe at the frequency of choice and you can be sure about the accuracy! This also ensures compatibility with your 10x and 1x probes as well.