Can NCV tester show presence of Knob & Tube wiring?
Yes your testing plan can work but you will need a load on the circuit to be sure. With no load on the circuit the NCV will only detect the hot, if the circuit is daisy chained as long as the last receptacle or outlet in the chain is loaded there should be the return voltage on the neutral and the tester should detect it. No load and only the hot will be detected so it would look like it was updated but may be K&amp;T. 
I have always liked using a plug in light but today’s LED’s may not have enough to be detected the field may be weak, a 60w lamp or a hair drier On low will work well .