Leakage current of ESD protection diode vs regular zener diode
You can use an OA that has ESD protected inputs. You need to add a current imiting resistor. 







simulate this circuit &ndash; Schematic created using CircuitLab







simulate this circuit

If you use very high impedance resistor divider, then the current can't be higher than 0.2 micro amp (5 giga resistor). The input ESD protection will easily limit the voltage. But you have to be aware that resistor divider has also a capacitance, so it is RC divider not a pure resistor divider.

Now if we look the capacitive part of the divider, you can see that output voltage is inversely proportional to the filter capacitor. If not placed, you could get very large spike on OA input. The capacitive divider takes its place when switching events occurs on the measured rail.







simulate this circuit