feedback of motor frequency using VFD analog output?

I use a vfd to rotate my spindle. my vfd has the option of a 4-20 or 0-10V analog output to provide feedback on the motor frequency.
is it possible to use this output on a 7i77 board as such? or do i need to invest in hardware?

If you don't need high resolution, the 7I77 has 4 analog inputs available

could this be considered for a tapping operation?

If you mean instead of a spindle encoder. no.