How can i convert switch
In one case in our house, the electrician installed a new cable (helper "fished" it in the attic) from the switch box to the location of the new ceiling box. The old cable to the receptacle was disconnected from the switch and the two wires connected with a wire nut. That receptacle is now always powered.

In our case the whole duplex receptacle was switched. In some cases only one receptacle of the duplex is switched and the other is always on. In that case the cable for the switch loop can simply be disconnected at both ends. At the receptacle end you would then need a short jumper or jumpers to replace the broken off tab or tabs. Or put in a new duplex with the tabs intact.

EDIT
There are different ways the switched receptacle can have been wired: 1. The hot feed cable enters in the switch box or 2. The hot feed cable enters in the receptacle box.

If you have case 1, then you will have both hot and neutral in the switch box. If case 2, then you might or might not have a neutral in the switch box. You need both hot and neutral in the switch box to work the light unless you power the light from some other source.