I have a Nucleo-IHM01A1 motor driver to drive a motor mounted with a spindle. The spindle has a limited length with an object in between. As the motor spins, the object moves along the spindle.
How can I set the Home position of the motor such that every time I run the program on the MCU, the Home position is set when the object is at the center of the spindle.
Unfortunately, the mechanical and electrical setup you describe does not actually allow automatic home calibration in a proper way.
Stepper Motors are used, as name suggests, to perform steps. They are not capable of absolute positioning on their own. If you need absolute positioning, you will have to either set your home point whenever the current position is unknown (eg. start-up or after losing steps), or add an absolute encoder to the system (then you always know the system state).
One solution for automatic home detection are limit switches, commonly used in many mechanical systems, especially 3D printers and other CNC machines. You might want to add one of these to your setup and drive towards the switch until it is pressed. Then you move it the exact number of steps needed to move it to the center and you're done.
However, if you can't change anything in the setup, you could just move the sled in one direction by the length of the spindle. When the sled hits the end, the motor should stall and loose the remaining steps. Then you move it back to the center (constant number of steps as previously) and you're centered. Consider that stalling motors can overheat the motor as well as the motor driver. This will probably decrease their life-expectancy.
There are other solutions like servos or absolute encoders but as far as I understand your goal, a limit switch should be fine.