It wasn't hard getting Alastor's attention. In fact, Moody had spotted Frank a while ago, walking his dog down the path in his direction. He noted him, but since Moody didn't see him as a threat, had decided to let Frank go about his business. When he heard his name called, Moody looked down, while his magical eye continued to spin, keeping watch of the area.
"Frank." He nodded a greeting. "Reckoned you'd be at the party tonight. Get up here."