Take a look at arcpy.mp, I think this gets you what you want:
aprx = arcpy.mp.ArcGISProject("CURRENT")
m = aprx.listMaps()[0]
lyrs = m.listLayers()
[(i, lyr.name) for i, lyr in enumerate(lyrs)]
returns
[(0, 'TestLine'), (1, 'TestPoint'), (2, 'TestPoint_Raster'), (3, 'TestPoly'), (4, 'TestPoint'), (5, 'World Topographic Map'), (6, 'World Hillshade')]