Thank you for reaching out. If you want to check the hex color value of the object. You can select the obejct and click on the fill in the property inspector there you will see the hex code for the color. Please see the attached screenshot below-
Let me know if I misunderstood your question. I will be happy to help.
So I am currently a sketch user and when I click any item I can immediaently see the # value without having to click on the fill button to bring it up. It makes things really easy, so I was wondering if I could do that? When a document is quite complex it's easy to quicly see which colour has been assigned to an object.