Totally agree with cmb, start with a divider. Depending on the probe, buffer the divided node with a follower.
Only if it doesn't work go to the more complicated integrators.
My only caution is 100M/1M is pretty big and even if there is only a few 10s of pF on the follower node (due to the opamp or probe) the measured signal will be low passed into KHz. As ~100KHz values are desired you might want to try lower value resistors.