Love the tinfoil kitten!
Actually, you can still get those dumbphones like they sold years ago.
No data plan, just minutes, and even text is an optional add on.
I am sure that there are still ways to 'bug' those types of phones as well, with access to the right technology, but most of those types of apps ask for your permission, so unless your spouse has your phone when you don't know about it, you should be okay.
You know, I say this a lot lately, but if anyone I know wants to monitor my activities, they are going to become quickly bored and move on, so unless your life is akin to an international spy, or you regularly take part in some rather clandestine activities, your spouse (or whoever) will probably see that there is no point in this, and move on rather quickly.
Never Lookin' Back!