From what I know there is no out of box control you can use.  I assume the number is per instance of  form. So if  I  have Form1 and Form2 using two different section site, each of them need to start from "1". To do that you need to create custom form elemnt.  See:

http://www.david-tec.com/2016/01/building-out-a-custom-form-element-with-the-new-episerver-forms/

And then behaviour of  it is perhaps in Dynamic Data Store  to store current "Number" associated  to each form. On  submit you just need to read DDS value associated to the form,  increase it and save it against value of control. 

Hope it helps

Thank you for help!