I am not sure I understand what you wish, so I will answer different, separate questions.
Are you asking how to repair your system, should your boot sector get corrupted? If so, the ideal utility for you is Boot Repair, a convenient Ubuntu-based utility. All you need to do is put on a USB stick a Ubuntu image (the one that you download in order to install Ubuntu), boot from the stick, choose at the appropriate screen "Try Ubuntu without installing it", then follow the instructions on the Web page I referenced above to download Boot-Repair, then run Boot-Repair using the standard instructions which, in my experience, are normally sufficient to solve most common problems. Please notice that the Ubuntu stick does not keep the downloaded package Boot-Repair (nor any other package, for this matter), so, if you run into the same problem again you will have to retrace the same steps.
Should this prove insufficient, you may go to this Web page of www.distrowatch.com which lists all distros useful for a system rescue. There are ten to choose from, most people find SystemRescueCd especially helpful, but there are other options.
Lastly, there is Remastersys, which is a fantastic utility, which can, according to Wikipedia:
Remastersys is a free and open source program for Debian, Ubuntu-based, or derivative software systems that can:
Create a customized Live CD/DVD (a remaster) of Debian and its derivatives.
Back up an entire system, including user data, to an installable Live CD/DVD.
You should not worry about the Live CD/DVD bit, because it is possible to transform a Live CD/DVD image into a bootable stick, easily, see here.
Now a word about Remastersys. It is in a transition phase because its creator, Fragadelic, has abandoned its development, and has picked it up again inside a different project. However, for the time being, you can still find the executables for Debian here, while details about the state of advancement of the new project can be found here.
Remember that, when you decide which of these solutions is right for you, you can post in this same forum (but different question) all requests for further clarification you may have.