Ubuntu – Note taking software that supports images

If Basket does what you need except for saving the stuff in the wrong place, you could just create a symlink from where Basket wants to save stuff to where you want it:

ln -s /media/truecrypt1/baskets ~/.kde/share/baskets

I don't know exactly what encryption software you use, but assuming that it lets programs read and write from the file system as long as you're logged in and have unlocked it, this should do what you need in terms of moving the baskets.

Joplin is probably what you're looking for. It supports Markdown, and thus can be used to store code snippets. It also supports Math expressions using the Katex notation. Notes can be exported to PDF directly from Joplin. And of course, it supports images too.

Joplin is a free and open source note taking and to-do application available for Linux, Windows, macOS, Android and iOS. Its key features include end-to-end encryption, Markdown support, and synchronization via third-party services like NextCloud, Dropbox, OneDrive or WebDAV.

For me, Joplin is the perfect Evernote alternative, and more, since it supports encryption, is open source and supports synchronization using a cloud sync service of your choice.