My problem is that I don't know keyname action for Mouse Click.
For example I want to remap F1 which keycode is 67 with a mouse click 1
I have to type:
xmodmap -e "keycode 67 = ??"
What I need to put in place of question marks (for mouse click)?
I don't think that it's possible using only xmodmap tool to accomplish what you wish. This because the mouse button is not a key, so it can't have a keyname.
One way to do what you wish is to use xdotool 
. Using the following command line you can simulate a left click of your mouse:
xdotool click 1
Now, all you have to do is to add a custom keyboard shortcut for the above command. You can't use the F1 key for a custom shortcut, but you can use for example F2 key, then use xmodmap to make F1 key to act as F2 key:
xmodmap -e "keycode 67 = F2"
