trackle is only suitable if your cycle is not affected by artificial hormones or other influences. With the IUD, a distinction is made between a hormone IUD and a copper IUD. 

While the copper IUD does not influence your hormones, the hormone IUD (also known as an intrauterine contraceptive ring or system) contains hormones that influence your cycle.

So if you are using a hormonal IUD, unfortunately you cannot use trackle at the same time. But maybe you will want to switch to natural family planning at some point? 

Here's a little insight into how trackle works.

Do you have a copper IUD? Then take a look here:

Can I combine trackle and a copper IUD / copper chain?