Rashi citing Targum Yonasan: If they will think to hide in a deep grave.

Radak: They cannot escape Me above or below. This is why it mentions the grave and Shamayim, like David said "Im Esak Shamayim Sham Atah v'Atzi'ah She'ol Hineka" (Tehilim 139:8). Chatirah is digging, like "va'Echtor ba'Kir" (Yechezkel 8:8).

Malbim: This explains "Lo Yanus Lahem Nas" (1). No kind of fleeing will help. If they dig a tunnel deep like a grave to hide there, My hand will take them and hand them over to the enemy. The same applies to one who ascends a high mountain.

Rashi citing Targum Yonasan: Via My word, their haters will take them.

Malbim: Refer to 9:2:1:3.

Rashi citing Targum Yonasan: If they will ascend tall mountains up to Shamayim (I will take them down with My word.)