Updated to Mojave at home, and the thing they replaced the simple "grab" tool with is a time-wasting abomination of needless complexity. Is there another option somewhere that works like the old grab tool?
The key combination of Shift+Command+3 (⇧+⌘+3) will capture the screen to the desktop while Shift+Control+Command+3 (⇧+^+⌘+3) will capture the entire screen to the clipboard. Likewise, ⇧+⌘+4 will capture part of the screen to the desktop and ⇧+^+⌘+4 will do the same to the clipboard.
Mojave has made that even easier. Just use Shift+Command+5 (⇧+⌘+5) and it will bring up the new screen capture utility that will let you decide if you want to capture full screen, part of the screen, and place it on the desktop or clipboard. So now there is only one key sequence to remember. More info here.