problem solved  ;-) short description and code for ADS1115 + SEN0464

first you need to calibrate ;-) more info on the webpage :
https://wiki.dfrobot.com/Gravity_Analog_ORP_Sensor_PRO_SKU_SEN0464

most important part:
Remove the ORP probe and use wire to short-circuit the S+ and S- pins of the ORP signal converter

use below code to read calibration value :

Adafruit_ADS1115 ads;
ads.setGain(GAIN_ONE);
ads.begin();
voltage = ads.readADC_SingleEnded(ORP_PIN);

//you will have calibration value 
calibration = voltage * 0.125;

and you will use it in your program to read data :

Adafruit_ADS1115 ads;
ads.setGain(GAIN_ONE);
ads.begin();

voltage = ads.readADC_SingleEnded(ORP_PIN);

orp = voltage * 0.125;
orp = orp - calibration;

just to clarify i got SEN0464  ORP probe