Capacitance is proportional to the overlapping area of the conductors involved and the distance between them. Decreasing the insulation or gap between them increases the capacitance.
OK, I agree. But should I check resistance of a capacitor or capacitance? Because when we talk about the insulation resistance we check it with meggar. We never talk about insulation capacitance.
You would check capacitance with a capacitance meter, or DMM that has that setting. You have to check capacitance on two wires running parallel that are not shorted together at any point.