Hello, Kanti
Thanks for your question.
To start, I think that you want to refer to UCS C240 M3 and not to UCS M240 M3.
Taking this into account, Cisco typically uses standard sizes for their server rack screws. Generally, most rack equipment uses 10-32, 12-24, or M6 screws.
In order to complement this, feel free to check the follow details about this topic:
I hope that this information can be useful to you.
Best regards.