Submenus on tablet and mobile devices can't be accessed.

My menu for my website has submenus. When you hover on a computer over the menu item, the submenus are displayed. When you tap the menu item on a touchscreen device, you go straight to that menu item without being able to access the submenu items.

How can we make this a two-tap process so that one tap opens the menu item and the second tap opens the linked item?