This is not possible with callbacks. You will need to use parallel processing and some way of communicating between the workers. Or you will need to rewrite the two routines to do a limited amount of work and then give up control so that the other routine can make progress.
You have the difficulty that both routines need to be in continual control in order to issue movement instructions to something, unless you can create or find devices such that you can can give it endpoint coordinates and it moves the object without the MATLAB session needing to give every motor spin.
