How to create a tension meter to show the tension applied to a rope

What i am trying to do is create a tension meter for a fishing game that i am working on. the purpose of it is to show the state of the fishing line (how close it is to breaking) when reeling in a fish.

the current way i am doing it, is that i have a configurable joint attached from the fishing line to a hook, and when the fish pulls too hard the joint breaks. All that works fine, but i have no way of displaying to the player how close it is to breaking

the way i am currently trying to do this is to have a slider with a min/max values of 0 and the joints break force respectively, then every frame set the sliders value to the current force applied onto the joint. however i have no way to find the force

I have looked online for tutorials and everything i find says that there is no way to find the current force applied onto a joint. what i'm asking is for some kind of work around, or formula to calculate the force myself. or if there is even an entirely different way of doing it