Every Shabbos we read a haftorah dealing with inyono d'yoma. Once in a while the inyono d'yoma happens to be that there is a chosson in shul or that today is erev Rosh Chodesh. But usually we consider the parshas ha'shavua as inyonei d'yoma, and there is always an obvious connection between the haftorah and the parsha. In parshas B'ha'aloshcho, both the chumash and the novi deal with the lighting of the menorah in the Beis Hamikdosh. Very often, in addition to the obvious connection, there is a deeper connection which is not that obvious. The Rambam lists the thirteen principles of faith of the Jewish religion. Two of these i'korei ha'emunah are 1) that we believe in prophecy and 2) that we believe that Moshe Rabbeinu was the greatest prophet of all times.
Regarding the uniqueness of Moshe Rabbeinu's nevuah the Rambam (in Moreh Ne'vuchim) points to the haftorah of parshas B'ha'aloshcha wherein the novi Zecharia is shown a vision/prophecy which he could not understand. Zecharia then asked the malach who showed him the vision to explain what the olive trees in the vision are supposed to represent. The malach responded, "but you certainly know what they are all about", whereupon Zecharia again requests of the angel to please explain because he didn't understand! Finally the malach explains the vision to the novi Zecharia.
The Rambam quotes the gemorah saying that Moshe Rabbeinu's level of prophecy was much greater than that of all the other nevi'im in several different ways. One of the differences is that the prophecies of Moshe Rabbeinu were much clearer than that of the other nevi'im. The Rambam quotes the passage from the novi Zecharia to demonstrate the point that unlike Moshe, it took Zecharia a while, with quite a bit of give, to understand the prophecy.
Moshe Rabbeinu being the greatest novi is one of the major themes of Ba'ha'aloscha. Moshe Rabbeinu's own sister, Miriam, made negative comments about her brother, not realizing that his level of prophecy was way beyond hers or that of her other brother Aharon. Hashem punished Miriam for the negative comments that she made and formulated this ikar in emunah, i.e. that all should realize that Moshe Rabbeinu was the adon ha'nevi'im. This is the additional connection between Ba'ha'aloscha and its haftorah - they both bring out this ikar in emunah.