First of all you need to perform a block level copy of disk to file similar to this:
dd if=/dev/sda of=/root/sda bs=1M
Of course the source volume needs to be unmounted and you will need enough disk capacity to fit the size of the whole source disk at the destination.
Download VirtualBox and look for The VboxManage.exe which can be found on the VirtualBox folder and run:
VBoxManage.exe convertfromraw myfile.dd myfile.vhd --format VHD