Do you want to be able to measure analog voltages with more resolution than your current Arduino UNO or other microcontroller? Then you need a device such as the ADS1115.
The ADS1115 is a 16-bit precision analog-to-digital converter capable of 860 samples/second over I2C. It has four input channels, which can be used as four single-ended, or two differential channels. See "Single-Ended Vs. Differential Analog Inputs" below for more information.
The module can be powered with supply voltages between 2V to 5.5V, which makes them compatible with all common 3.3V and 5V microcontrollers and processors, such as Arduino and Raspberry Pi.
The module's I2C address can be configured for one of four available addresses making it possible to connect up to four of these modules to the same I2C bus. So, you can effectively add up to 16 additional analog inputs to your Arduino or other microcontroller. See the "I2C Address Selection" section below for details on configuring this address.
It includes a programmable gain amplifier (PGA), which can be configured for gains up to x16, to amplify small analog signals to the full available range.
If you want to measure voltages much higher than the max analog input (AIN) then you can use a couple of resistors to make a voltage divider that will give you a voltage within the range of this module and then use this module to precisely measue that voltage.