我可以使用我的交换内存来增加 Ubuntu 20.04 的存储吗？

Use disk management tool gparted. If not installed you can install it using $ sudo apt update && sudo apt install gparted. Launch the app as a super user $ sudo gparted and enter the password when prompted. You will see the logical representation of your storage device.

It is possible to make these changes if and only if your swap partition is adjacent to the right of the root partition otherwise you are limited! If this is true, proceed to swapoff and resize your partition from left to right creating an unallocated space adjacent to the right of the root partition. After that move the root partition to the right adding the an unallocated space. A green icon should appear to the top asking to apply all changes. Click and proceed as prompted and you are good to go.

For detailed information on how to use gparted find it here.

希望这可以达到您的目的。成功！