Steps:
1. F2 - Boot Menu
2. Set Password
3. Choose UEFI only Not Legacy
4. use rufus (https://rufus.akeo.ie/) to create Bootable USB
5.Choose Location 'something else'
6.Primary, Mount point is /
6. for Device Boot location, Selecting the Boot EFI partition as the device for boot loader installation
or
Under "Device for boot loader installation":
- if you choose dev/sda, it will use Grub (Ubuntu's boot loader) to load all systems on this hard drive.
- if you choose dev/sda1, Ubuntu need to be manually added to drive's boot loader after installation. (for example, you previously have Windows installed on another partition of this drive, you'll need manually add Ubuntu into mbr)
7. Download updates check all boxes, no time waste
8.Done
Refrence : http://linuxbsdos.com/2015/09/07/how-to-dual-boot-ubuntu-15-04-with-windows-10-on-a-single-hard-drive/