READ OUT LOUD. Choose which marked text you prefer to practice with - macrons in verse form, or macrons in prose order, or accent marks in prose order, or focusing on the meter. You will find materials for all of these options below. :-)
VERSE MACRONS. Here is the verse text with macrons:
Lūnārem noctū, ut speculum, canis inspicit orbem,

Et lātrat: sed frustrā agitur vox irrita ventīs,

PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Canis orbem lūnārem noctū inspicit, ut speculum, et, sē vidēns, crēdit canem alium inesse, et lātrat: sed frustrā vox irrita ventīs agitur, et Diāna, surda, cursūs suōs peragit.
STRESS (ACCENT) MARKS. Here is the prose text with accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Canis orbem lunárem noctu ínspicit, ut spéculum, et, se videns, credit canem álium inésse, et latrat: sed frustra vox írrita ventis ágitur, et Diána, surda, cursus suos péragit.
ELEGIAC COUPLET METER. Below I have used an interpunct dot · to indicate the metrical elements in each line, and a double line || to indicate the hemistichs of the pentameter line.
Lūnā·rem noc·t~, ut specu·lum, canis· inspicit· orbem,

Et lā·trat: sed· frustr~ agi·tur vox· irrita· ventīs,

IMAGE. Here's an illustration for the fable (image source) from a 1621 edition of the emblems:

What follows is an unmarked version of the prose rendering to faciliate word searches: Canis orbem lunarem noctu inspicit, ut speculum, et, se videns, credit canem alium inesse, et latrat: sed frustra vox irrita ventis agitur, et Diana, surda, cursus suos peragit.