(Im reffering youas the detector)
In case of cloak there should be some units technology of detection. Like lvl 1 cloak vs lvl 1 detect the you see only a ''bleep''
on the map. On lvl2 Cloak vs lvl 1 detect. You dont know that there is anything there at all. On lvl1 cloak vs lvl 2 detect you see the exact number and type fleet quantity etc.
There should be like 1-5 in cloak and 1-5 in detect something like that.
And to be nice you can build cheap fast 1turn built: Deciever which acts as a fake giving of a bleep, if you build several the ''real'' fleet can go in without much trouble.Which then just moves up to the main planet and sais ''Hello!''