Hi, @marie2808
Welcome to the forum.
Your circuit for all to see.
I certify kV level insulation testers.
The safest I have seen is one that produces up to 15kV with a transformer and Cockcroft type multiplier.
The voltage feedback is provided by a scaling measuring network on the output terminals, it is supplied by a DC to DC converter with 20kV isolation.
The monitor network PCB then communicates with the controller via two optical fibre cables.
Can you please tell us your electronics, programming, arduino, hardware experience?
What is the actual project and what is it for?
15kV is not a voltage to be just fed to a PCB and potential divider scaled down to digital 5V level.
Tom.... 
