JSONForms: How can I get the value of an element in uischema

Question

    {
      type: "Control",
      scope: "#/properties/prop1",
    },
    {
      type: "Control",
      scope: "#/properties/prop2",
      rule: {
         effect: "DISABLE",
         condition: {
             scope: "#/properties/prop1",
             schema: {
                 ...
             }
         }
      }
    }

How can I get the value of prop1 so I can use it in the condition for prop2?

I need to disable element2 based on prop1 input value.