How to add custom variable/attribute in camunda tables

I am trying to get introduced a new variable in the modeler and get stored its value in any one of the tables and retrieve it back.

@pinturjs, Runtime variables will be persisted in ACT_RU_VARINST table.

public void setProcessVariablesToInstance(String processInstanceBusinessKey) {
    Execution execution = runtimeService.createExecutionQuery().processInstanceBusinessKey(processInstanceBusinessKey)
        .singleResult();

    CustomerDTO customerDTO = CustomerDTO.builder().id("C3462").name("Camunda").address("Germany").build();

    ObjectValue customerDataValue = Variables.objectValue(customerDTO)
        .serializationDataFormat(Variables.SerializationDataFormats.JAVA).create();

    Map<String, Object> variableMap = new HashMap<>();
    variableMap.put("customerDataValue", customerDataValue);
    variableMap.put("category", "politics");
    variableMap.put("activeStatus", true);

    runtimeService.setVariables(execution.getId(), variableMap);    

    StringValue typedStringValue = Variables.stringValue("a string value");
    runtimeService.setVariable(execution.getId(), "stringVariable", typedStringValue); 
  }