Radio -> cable -> cellphone audio jack -> APRS app
If you have an iOS device probably using a lightning / usb-c to 3.5” TRRS jack too.
Radio: https://www.amazon.com/Baofeng-UV-5R-136-174-400-480Mhz-1800... Cable: https://www.amazon.com/BTECH-APRS-K1-Interface-APRSDroid-Com...
While this works, it is just the start. Soon you realize that you want to actually use your phone AND APRS at the same time and that your audio and mic are busy. I did this for about a day before seeking out something better.
Radio -> cable -> Mobilinkd Bluetooth TNC paired to your phone -> APRS app
Now you can take calls, play music in the car and drive down the road with a radio paired and use APRS. This isn't a bad setup, the big pro us the multitasking and using the APRS app on your phone to write messages.
The other way I've done this is a radio that has the TNC and APRS built in. A handheld like the Kenwood TH-D74 can send and receive messages without any additional hardware, but you have to write the messages on a lame keypad like in the dumb phone days. I like this for backpacking as there are fewer pieces to worry about.
It is fun stuff, and can be a life saver. Check out https://hamstudy.org/ the easiest level (Tech.) is enough to get you access to all of this.
Also 100% recommend anyone interested getting their Amateur Radio Technician license. TBH you can pass the test with an afternoon of study, and the advanced licenses are really only needed for additional HF spectrum privileges.