Apparently what you are seeking is a way to read the voltage of the wires by piercing but not cutting the insulation. It's called pick probing. You will need a few, very sharp dental instruments that can pierce through the insulation of the wire just enough to make contact with the wire. The handle end of the instrument will be attached by an alligator clip to the meter you are using. When you remove your pick, the pin prick in the insulation will be so slight as to need no remediation to the wire or its insulation
(I've only been using this technique for 40 years. If you find it useful a 'thank you' would be appreciated.)
