How should I measure the water temperature of my loop?

Hello, I'm new to water cooling my pc and I wonder how I'm supposed to measure the temperature of my first loop.

I read that the temperature of the water in the loop is more important than the temperature that the CPU runs at because the temperature of the water changes much slower and you pretty much just want to hold it at a steady temperature that cools the CPU to a temperature that you feel comfortable running.

I want to measure the water temperature so that I can read out the temperature from within Windows and create custom fan/pump curves that respond to my current water temperature and not the fluctuating CPU temperature because I want near silent operation at idle or watching videos but also high cooling performance when my CPU is under heavy load.

All I have found online are these inline probes but I don't find any way to connect these to my system.

My current System (I only want to cool the CPU for now):
*Intel Core i5 4670k
*ASUS z87m-Plus
*NZXT H440
*GTX 660Ti
*SSDs/HDDs/etc.

The Problem is that I can't use any front mounted bay because the H440 doesn't have any and I don't want to change any values manually once I have setup the fan/pump curves.
A possible solution would be using a internal controller like the Aquaero 5 LT but this controller is overkill for controlling one pump and one/two fans and a singe sensore especially at a price of around 60€. An alternative would be a risky RAM mod that allows access to the SMBus that I found on Madhacker.org that I would need to do because my mainboard does not have a SMBus header but I dont want to risk my RAM just for this and in my opinion it doesn't even look very clean/nice.

I want a cheap and easy solution that does not force me to mod my current components and works similarly like the NZXT Grid+ but for sensors.

Thanks for the help in advance.