I want to write on paper more often, but one thing that keeps me from doing that is the feeling of a loss of privacy. I encrypt my notes on the computer. I like knowing that no one can read it - now or even when I am dead. Any suggestions?
If you are worried about that, you have to be really careful with OPSEC.
The "look over your shoulder" attack is omni-present. (Also easier to prevent with paper, in general, than with a larger computer screen.)
A simple safe will stop most prying people. And if you die... Well, you are dead... there ain't much stopping anyone at that point.
Keeping secrets is hard. Very hard. There's a reason for the most part... I don't bother, except if/when I need to, and even then, if they can be timed out, all the better.
Paper also has a big benefit in that we know how to destroy it. :)
... Simple things are often best. Understanding how your system will bend/break is critical in security situations.
Not OP, but you seem to be thinking about this in a particular way. There are some things I don't want to be read, but not in the sense that they're "high value" in a way that would attract motivated attackers. I'm not worried that my friends and family are going to shoulder surf, trick me, hack my devices, or threaten me with a big wrench to get at my private thoughts.
For these purposes, written journals or letters can be opened opportunistically if found. If I had a safe, it would be opened after my death. If the documents are known to exist in the clear anywhere, then they're subject to probate.
But if they're encrypted and the secret is unknown and hard to guess, then most likely everyone gives up and that's the end of that.
It's not a very rational fear. But there's a freedom that comes from knowing that nobody will read what you're writing; similar to the freedom you get from the anonymity on HN.
iPad + Apple Pencil + OneNote (encrypted end-to-end)
If you lose your onenote encryption key, your data is lost forever.
Another solution is Apple Notes with Advanced Data Protection turned on for your Apple ID. That encrypts your entire iCloud Drive with your encryption key and again if you lose your key data is gone; although there are some recovery options which require a trusted contact.